JP2007278928A - Defect inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect inspection device which can quickly extract required information from a sample, such as a substrate and perform inspection promptly. <P>SOLUTION: The defect inspection device 1 has a camera 25 which acquires a surface image of the sample by scanning in the one axis direction. The output of the camera 25 is constituted to receive from/deliver to an image capturing circuit 31 of a control part 3. The image capturing circuit 31 creates only images in a defect region and performs image processing by acquiring image data captured from the camera 25 with sectioning an image pick-up start trigger, a capture start pixel position and a capture end pixel position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a defect inspection apparatus used for defect inspection of a substrate.

  In the manufacturing process of a semiconductor wafer, a liquid crystal glass substrate, a printed wiring board, etc., a defect inspection for inspecting a substrate surface for defects using a line sensor camera is performed. As a defect inspection apparatus used for such defect inspection, an image reading apparatus that reads an image of an imaging object using a line sensor camera is used (for example, see Patent Document 1). In this type of image reading apparatus, the line sensor camera is configured to be partially shielded by a mask plate. The same line sensor camera is used for various types of electronic components, and a mask plate is used in accordance with the size and shape of the object to be imaged. Since the light is received only in the necessary range of the line sensor camera, the image size can be reduced.

As a method for detecting defects, two-dimensional original image data obtained from a line sensor camera is compressed, image processing is performed on the compressed image data to detect defect positions, and defects are detected from the original image data. An apparatus that restores an image of a position is known (see, for example, Patent Document 2).
JP 2002-77874 A JP 2002-83303 A

  In general, during the manufacturing process of a semiconductor wafer, a liquid crystal glass substrate, etc., a photolithography process is performed in which a pattern is transferred after a resist is applied after forming a film on a substrate made of silicon or a glass plate. . In such a process, if the resist applied to the substrate surface has film unevenness or dust adhesion, it may cause defective line width of the pattern after etching or cause defects such as pinholes in the pattern. Become. Therefore, in the process before etching, it is usual to inspect all the presence of defects.

Here, even when a defect is detected using a defect inspection apparatus, the defect detected by the image processing is reconfirmed in detail by visual observation or a microscope in order to clarify the cause of the defect at an early stage. . In other words, early detection of defects and early clarification of the causes are indispensable for realizing a reduction in the defect rate of substrates and the like.
After that, when the manufacturing process is stabilized, the defects on the substrate which have appeared until then are hardly seen. In this case, even if the total inspection is continued, a plurality of predetermined regions on the substrate may be selected, and only the selected region may be inspected to determine pass / fail. In addition, when inspecting the edge cut amount and distribution of the wafer, the inspection is performed only on a predetermined area of the wafer edge portion, and the quality is determined.

However, in recent years, improvement in inspection resolution has been demanded, and the size of image data has increased. When the data size increases, the data processing takes time, which causes a long inspection time. In particular, when the substrate is enlarged, such a problem becomes remarkable.
The present invention has been made in view of the above-described circumstances, and a main object thereof is to quickly extract necessary information from a subject such as a substrate so that a test can be quickly performed.

  The present invention that solves the above-described problems is an imaging unit that captures image data as optical image information of a subject, and an image that generates compressed image data by compressing the image data captured by the imaging unit as an original image A compression unit; a defect extraction unit that extracts a defect region including a defect of the subject from the compressed image data; and a region designation unit that designates the defect region extracted by the defect extraction unit, and the region designation The defect inspection apparatus is characterized by performing defect inspection on the original image data of the area specified and acquired by the section.

  In this defect inspection apparatus, compressed image data is used at the stage of extracting defects. When the presence of a defect is recognized in the compressed image data, an image of a region where the presence of the defect is recognized is acquired from an uncompressed original image. Further, a detailed inspection is performed by comparing the extracted original image with previously registered defect information.

  According to the present invention, the defect extraction is efficiently performed using the compressed image data, and the inspection such as comparing the original image with information about the registered defect is performed on the defect extracted region. , Defect reconfirmation and detailed inspection can be performed.

A first embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the defect inspection apparatus 1 acquires an image of the subject W and performs an inspection, and captures the image of the subject W while controlling the inspection unit 2 to perform image processing. There is a control unit 3 that performs preprocessing, an image processing unit 4 that performs image processing in response to information from the control unit 3, and an image storage unit 5 that stores image-processed defect images, determination results, and the like. is doing.

  As shown in FIGS. 1 and 2, the inspection unit 2 includes a scan stage 10 (holding unit), and the scan stage 10 is provided with a scan stage driving unit 11 including a motor 11A. The scan stage drive unit 11 is a drive unit that moves the rotary stage 12 (holding unit) mounted on the scan stage 10 in a linear direction indicated by an arrow A. The rotary table 12 is rotatable in the rotation direction indicated by the arrow B by a rotary stage drive unit 13 including a motor 13A mounted therein. The rotary stage drive unit 13 is a drive unit that performs alignment of the subject W such as a glass substrate or a wafer in the rotation direction. A table 14 is mounted on the upper end of the rotary table 12. The table 14 is connected to the adsorption electromagnetic valve 15 and can fix the subject W by vacuum adsorption.

  An illumination unit 20 is disposed above the table 14 toward the subject W. The illumination unit 20 includes an illumination light source and an optical system. As a light source for illumination, for example, a lamp house including a halogen lamp, a heat ray absorption filter, and a condenser lens is used. The illumination optical system uses, for example, a condensing lens that converges a light beam from a lamp house and a fiber bundle in which an emission end is formed in a straight line for performing line illumination. The illumination unit 20 illuminates the subject W at an incident angle θ0, and a cylindrical lens 21 and a slit 22 for converging the light beam are disposed between the illumination unit 20 and the subject W. The illumination unit 20, the cylindrical lens 21, and the slit 22 are configured integrally, and the angle with respect to the surface of the subject W can be arbitrarily changed by the illumination angle driving unit 23. For example, the incident angle is larger than the incident angle θ0. It is also possible to illuminate the surface of the subject W with θ1.

  Further, a line sensor camera 25 (imaging unit) that acquires optical image information of the subject W is disposed above the stage 14 so that the reflected light from the illumination unit 20 can enter. In the line sensor camera 25, a plurality of image sensors (sensors) are linearly arranged in a direction orthogonal to the scanning direction, and a linear region of the subject W is imaged. A filter 26 is provided between the line sensor camera 25 and the subject W. A narrow band filter is used for the filter 26 so as to obtain an interference image by limiting the wavelength band of the illumination light. The filter 26 is inserted into and removed from the optical path, and the type of the filter 26 is switched. Can be done.

  The various sensors 28 of the inspection unit 2 shown in FIG. 1 are sensors that enable the inspection to be performed correctly by detecting the suction and holding of the subject W, the inclination angle of the illumination unit 20, and the like. The operation input unit 29 is for accepting the operation of the operator and performing various processes described later. And the inspection part 2 comprised in this way is accommodated in the dark box-shaped housing | casing not shown so that it may not receive the influence of external light. Further, in order to prevent particles from adhering to the subject W, a down flow flows from the upper part of the housing through the air cleaning filter.

Next, the control unit 3 includes an image capturing circuit 31 (image capturing unit). The image capturing circuit 31 captures one line of data captured by the line sensor camera 25 in synchronization with the movement of the scan stage 10 or in synchronization with the rotation of the rotary stage 12. A process of stitching the data of one line vertically (moving direction of the stages 10 and 12) is performed, and the entire subject W is converted into one two-dimensional image (original image).
A correction unit 32 is connected to the image capturing circuit 31. The correction unit 32 performs various corrections on the original image data. For example, the light distribution of the illumination unit 20 is generally not uniform, and the irradiated portion of the subject W has uneven light intensity. Moreover, the sensitivity of each image sensor of the line sensor camera 25 is not equal. For this reason, it is known that shading appears in the output data of the line sensor camera 25. The correction unit 32 uses the shading data stored in advance to correct the original image data so as to correct the original image. When various lenses are inserted on the optical path from the illumination unit 20 of the subject W to the line sensor camera 25, the output data of the line sensor camera 25 is distorted due to lens variations, aberrations, and the like. Such distortion is also corrected to an image multiplied by the original magnification by using distortion data stored in the correction unit 32 in advance.

An image preprocessing unit 33 is connected to the correction unit 32, and preprocessing such as filtering can be performed as necessary. An image compression unit 34 and an image storage unit 35 are connected to the image preprocessing unit 33.
The image compression unit 34 performs a process of compressing the original image data and reducing the image size by calculation with adjacent pixels on the original image data preprocessed by the image preprocessing unit 33. As an image compression method, for example, each pixel data in a 2 × 2 pixel area is averaged, data other than the maximum luminance data in an 8 × 8 pixel area is discarded, and conversely, data other than the minimum luminance data is used. Can be selected, such as truncating.
The image storage unit 35 can store arbitrary images in addition to the original image data output from the image preprocessing unit 33, the image data compressed by the image compression unit 34, and the like, and can read these images. ing. In addition, a process of cutting out the area specified by the area specifying unit 36 from the original image data is performed. The image storage unit 35 can output image data to the defect extraction unit 41 and the defect classification unit 42 of the image processing unit 4.

The region specifying unit 36 receives a command from the operation input unit 29 or receives a command from the image processing unit 4 and specifies a region of an image acquired from the subject W to the drive control unit 37. Further, it instructs the image storage unit 35 to extract image data of a predetermined area from the original image data and the compressed image data.
The drive control unit 37 controls the movement of the subject W and various drive units of the above-described optical system. The drive control unit 37, the scan stage drive unit 11, the illumination angle drive unit 23, The rotary stage drive unit 13, the adsorption electromagnetic valve 15, and various sensors 28 are connected. Based on the region specified by the operation input unit 29 and the defect region extracted by the defect extraction unit 41, each drive unit and the image capturing circuit 31 are controlled, and only the region specified by the region specifying unit 36 is imaged. Data can be captured by the image capture circuit 31.

The image processing unit 4 connected to the control unit 3 has a defect extraction unit 41. The defect extraction unit 41 receives the image data stored in the image storage unit 35, removes the inspected object outer shape image that is a unique image of the subject W, the specific pattern image, and the like, and uses pattern matching or the like. To extract defective areas. In addition, the region specifying unit 36 is notified of the region from which the defect has been extracted.
The defect classification unit 42 classifies the defect by comparing the image of the defect area extracted by the defect extraction unit 41 with the data stored in the defect dictionary 44, and specifies the defect type. Defect information (defect classification and type) is created for the identified defect.
The defect determination unit 43 regards a defect as a non-defective product if no defect is extracted by the defect extraction unit 41. When a defect is extracted by the defect extraction unit 41, the defect is detected from the content of the defect information specified by the defect classification unit 42. It is determined whether or not it exists in W. Further, it is determined from the content and position of the defect whether or not the subject W can flow downstream of the production line. Data used as a criterion for determination here is pre-registered data. The determination result of the defect determination unit 43 is transferred to the image storage unit 5.

  The image storage unit 5 includes an image determination result storage unit 51. The image determination result storage unit 51 includes the original image data of the defect area extracted by the defect extraction unit 41, the original image data of the defect area when imaged under different imaging conditions, and the types of defects classified by the defect classification unit 42. And name information, determination results in the defect determination unit 43, and the like are stored.

Next, the operation of this embodiment will be described.
First, a plurality of specimens W sent from the upstream of the production line are loaded and set on a carrier (not shown) by a human hand or a transport device of the production line (hereinafter referred to as a transport device or the like). After that, when the inspection start is input to the operation input unit 29 in FIG. 1 by the transfer device or the like, the defect inspection apparatus 1 starts to operate.

  The transport device or the like takes out a specific subject W from the carrier, and accurately places the subject W on the table 14 with the eccentricity removed. When the subject W is accurately placed on the table 14, the drive control unit 37 in FIG. 1 turns on the adsorption electromagnetic valve 15 to attract and fix the subject W on the table 14. Thereafter, the drive control unit 37 issues a command to the scan stage drive unit 11 to move the scan stage 10, and moves the peripheral portion of the subject W within the measurement region of the notch detection sensor included in the various sensors 28. Further, the drive control unit 37 issues a command to the rotary stage drive unit 13 to rotate the rotary stage 12. When the notch detection sensor detects the notch at the peripheral edge of the subject W, the position is registered with reference to the position. Thereafter, the rotary stage 12 is rotated so that the rotation position of the subject W is always the same.

  When the rotational positions of the notch detection sensor and the rotary stage 12 are determined, the drive control unit 37 issues a command to the filter drive unit 27 to extract the narrow band filter 26 from the optical path. Further, a command is issued to the illumination angle driving unit 23 to adjust the angle so that the illumination unit 20 illuminates the subject W at an incident angle θ1, for example. Since the preparation stage has been completed up to this point, the illumination unit 20 illuminates the subject W and starts to acquire the entire image.

  The illuminating unit 20 illuminates the subject W. Of the luminous flux emitted from the illuminating unit 20, an unnecessary diffusing luminous flux other than the incident angle θ1 is blocked by the slit 22, so that it is incident at an incident angle θ1. Only the light that hits the subject W. At this time, since the line sensor camera 25 is disposed at an angle θ0 ′ with respect to the subject W, the subject W is in a dark field illumination state when there is no unevenness on the subject W, and the surface of the subject W is on the surface of the subject W. The regularly reflected light beam does not form an image on the line sensor camera 25. However, when the subject W has scratches, dust, defects, or a normal pattern, a light beam scattered at a reflection angle θ0 ′ (= θ0) is generated in a light beam incident at an incident angle θ1. The reflected light forms an image on the line sensor camera 25.

  The line sensor camera 25 converts the imaging light into an electrical signal and outputs it to the image capturing circuit 31 for each line. The drive control unit 37 outputs an imaging start trigger signal to the image capturing circuit 31 and starts scanning the scan stage 10 in the uniaxial direction indicated by the arrow A. As a result, the subject W moves with respect to the line sensor camera 25. Therefore, when the data output from the line sensor camera 25 are added in the order in which they are taken, an overall image of the subject W is obtained.

  A specific example of the processing so far will be described with reference to FIG. In FIG. 3, the horizontal direction indicates the scanning direction of the scanning stage 10, that is, the passage of time. The vertical direction corresponds to the arrangement of the pixels (light receiving surface) of the line sensor camera 25. In response to the imaging start trigger signal, the image capturing circuit 31 starts receiving an electrical signal (image data) output from the line sensor camera 25. The image capturing circuit 31 starts capturing from the capture start pixel position SP without capturing electrical signals at both ends of the image LP for one line, and ends capturing at the capture end pixel position EP. The capture start pixel position SP and the capture end pixel position EP are defined in advance in the drive control unit 37, and the region where the subject W is within the captured range and the subject W does not enter is cut to cut the image. The data size is set to be small.

  Furthermore, the number of lines (capture line number) for capturing an image from the imaging start trigger signal is also determined in advance by the drive control unit 37, and the image capture circuit 31 captures an image by the number of capture lines. As a result, the capture area CA becomes a square image obtained by adding the images from the capture start pixel position SP to the capture end pixel position EP by the number of capture lines. The capture area CA is smaller than the area (imaging area PA) that forms an image on the line sensor camera 25.

  The data corresponding to the image of the capture area CA acquired in this way is subjected to shading correction using the shading data stored in advance by the correction unit 32 to correct the original image. In addition, distortion correction is performed using distortion data stored in advance, and the image is corrected to the original magnification. Further, if necessary, after performing filtering or the like in the image preprocessing unit 33, the original image data (two-dimensional image data) of the entire subject W is constructed and stored in the image storage unit 35.

Next, compression processing is performed on the original image, and the defect size is extracted after reducing the data size.
The image compression unit 34 compresses the original image data by calculating the proximity image from the original image data to reduce the image size, and creates compressed image data. For example, if the average of 5 × 5 pixels is taken and compressed to 1 pixel, the image data size can be reduced to 1/25 of the original image. The compressed image data is stored in the image storage unit 35.

  The compressed image data stored in the image storage unit 35 is sent to the defect extraction unit 41 of the image processing unit 4 and compared with an image of an ideal non-defective object stored in the image storage unit 35. After removing the subject outline image, the exposure range outline image, the specific pattern image, and the like, which are unique images of the subject W, the difference from the image with the non-defective subject is extracted by image processing. The predetermined area including the difference is handled as an area (defect area) determined by the defect extraction unit 41 as a defect. The coordinate data of the defect area extracted by the defect extraction unit 41 is sent to the area designation unit 36.

Next, the defect inspection apparatus 1 acquires again the image of the defect area, acquires only the image of the necessary area as an uncompressed image, and enables the defect to be inspected in detail with high accuracy. Moreover, you may enable it to test | inspect by changing imaging conditions as needed.
Here, the drive controller 37 issues a command to the filter driver 27 to insert the narrowband filter 26 on the optical path. Further, if necessary, an instruction is given to the illumination angle driving unit 23, and a condition different from the condition when the entire subject W is imaged is set so as to inspect in detail, and the subject W is illuminated at an incident angle θ0. The illumination unit 20 is set as follows. Here, the imaging angle of the line sensor camera 25 may be changed. The region designating unit 36 sets the timing for outputting the imaging start trigger signal to the drive control unit 37 based on the coordinate data of the defect region input from the defect extracting unit 41, and further captures the image capturing circuit 31. Set the number of lines, capture start pixel position, and capture end pixel position. The drive control unit 37 in FIG. 1 issues a command to the scan stage driving unit 11 to move the scan stage 10 on which the subject W is placed in the uniaxial direction indicated by the arrow A. An imaging start trigger signal is output from the drive control unit 37 to the image capturing circuit 31 at the timing set by the region specifying unit 36.

  The line sensor camera 25 takes in the reflected light of the subject W illuminated by the illumination unit 20 and converts the imaged light into an electrical signal. The electric signal is output to the image capturing circuit 31 for each line. At this time, the image capturing circuit 31 does not capture an image until the imaging start trigger signal generated by the drive control unit 37 is input, and is specified by the region specifying unit 36 from the line when the imaging start trigger signal is input. The electric signal is captured only up to the number of captured lines. Further, in each capture line, only an electric signal between the capture start pixel position and the capture end pixel position is captured.

  A specific example of the processing so far will be described with reference to FIG. When eight defect areas DA1 to DA8 are extracted by the defect extraction unit 41, the area designation unit 36 captures an imaging start trigger signal, the number of capture lines, a capture start pixel position, and a capture end pixel position for each defect area DA1 to DA8. Is calculated and set. For the defect area DA1, the imaging start trigger signal T1, the number of capture lines corresponding to the image length LG1 in the scan direction, the capture start pixel position SP1 corresponding to the image length WH1 in the length direction of the line sensor camera 25, and A capture end pixel position EP1 is set. The line sensor camera 25 continuously acquires images including the subject W, but the image capturing circuit 31 receives only the number of capture lines for the electrical signals in the range from the capture start pixel position SP1 to the capture end pixel position EP1. . As a result, only the defect area DA1 corresponding to the image length LG1 × the image length WH1 is captured. The image size of the defect area DA1 is sufficiently smaller than the imaging area PA1 of the line sensor camera 25 corresponding to the image length LG1.

  Hereinafter, images are captured in the same manner for the other defective areas DA2 to DA8. The defect area DA7 and the defect area DA8 have a part that overlaps in the scanning direction. In this case, image capture from the capture start pixel position SP8 to the capture end pixel position EP8 in one line, Image capture from the capture start pixel position SP7 to the capture end pixel position EP7 is performed in parallel. The image sizes of the defect area DA7 and the defect area DA8 are sufficiently smaller than the imaging area PA2 of the line sensor camera 25 corresponding to the image length LG2.

  The correction unit 32 similarly performs shading correction and distortion correction on the data of only the defective area thus designated, and after performing filtering or the like in the image preprocessing unit 33 if necessary, the original data for each defective area is obtained. Image data is constructed and stored in the image storage unit 35. At this time, similarly to the above, the image compression unit 34 may compress the original image data as necessary and store it in the image storage unit 35. The image storage unit 35 sends the original image data or the original image data captured by changing the illumination angle condition as necessary to the defect classification unit 42.

The defect classification unit 42 reads the defect information stored in advance from the defect dictionary 44 based on the detailed image data of the defect area, compares it, and specifies the type of defect. The name of the defect registered beforehand is given to the characterized defect. From the content of the defect information created in this way, the defect determination unit 43 determines whether or not a defect exists in the subject W, and determines whether or not the subject W can flow downstream of the production line. To do. For example, when the defect is in a position that does not affect the quality of the product, or when the defect has a size that does not affect the quality of the product, it is determined that the defect may flow downstream of the production line. If the defect affects the quality of the product, an instruction is output to remove the subject W from the production line as a defective product. In this case, the subject W is automatically removed from the production line, or the worker who has received the notification removes the subject W from the production line.
Then, after the pass / fail determination is performed by the defect determination unit 43, the original image data of the defect area extracted by the defect extraction unit 41, the original image data of the defect area captured by changing the imaging conditions, the defect information, and the defect determination unit 43 The determination result and the like are stored in the image determination result storage unit 51 of the image storage unit 5.

  According to the present embodiment, compressed image data is created from an image of the entire subject W, and defects are extracted using the compressed image data. Therefore, compared with the case of processing large-capacity original image data. Inspection time can be shortened. After performing defect extraction with compressed image data, an uncompressed image of the extracted area is obtained again, so that a detailed inspection of the defective area can be performed using the uncompressed image. It becomes possible. Since only the image of the defective area is acquired, the time for image processing or the like can be shortened. Furthermore, when acquiring only the extracted defect area again, instead of using a mechanical mask or the like on the line sensor camera 25 side, only the information necessary for the processing of the control unit 3 is extracted. The apparatus configuration can be simplified, and the acquisition area can be flexibly changed. Furthermore, when the image capturing conditions are changed and the image is acquired again, it is possible to perform a more detailed and accurate inspection.

A second embodiment of the present invention will be described in detail with reference to the drawings.
This embodiment is mainly characterized in that the peripheral edge portion (wafer edge portion) of the wafer is inspected. In other words, if production is continued with cracks occurring on the wafer, the wafer may break during production, so it is desirable to determine the quality of the wafer by detecting the presence or absence of cracks at the wafer edge as early as possible. It was.
In the photolithography process, after a thin film of photoresist is applied on the surface of the wafer, an appropriate amount of a rinsing liquid is dropped to cut the photoresist on the periphery of the wafer by a predetermined width to expose the wafer edge portion. This is to prevent particles from being generated from the photoresist that unnecessarily travels to the back surface and causing defects.
In the present embodiment, the inspection of the wafer edge portion at this stage is an important inspection item for manufacturing a good semiconductor wafer by proceeding with the subsequent processes. It is. Note that the apparatus configuration is the same as that of the first embodiment, and a duplicate description is omitted.

  In the measurement of the edge cut line width of the subject W that is a wafer, the entire area of the wafer edge portion is not measured. For example, the edge cut line width of the subject W is measured at a total of four positions shifted by 90 degrees in the circumferential direction. The distribution of the wafer edge portion can be assumed only by measurement. Hereinafter, the operation will be described from the start of the operation of the apparatus when the start of inspection is input to the operation input unit 29.

First, a measurement region is set in the region designation unit 36 from the operation input unit 29 in FIG. The area to be set is an area corresponding to the wafer edge portion every 90 ° as described above.
The region designating unit 36 sets the number of pulses for outputting the rotation stage imaging start trigger signal to the drive control unit 37 based on the set region, and further the number of capture lines, the capture start pixel position, and the capture end in the image capturing circuit 31. Set the pixel position. When an examination start signal is input from the operation input unit 29, the subject W is positioned as in the previous embodiment, and then the drive control unit 37 in FIG. Is moved to a position where the imaging line of the line sensor camera 25 and the center of the subject W overlap.
Next, the drive control unit 37 issues a command to the rotary stage drive unit 13 to rotate the rotary stage 12 on which the subject W is placed by 180 degrees. At this time, an imaging start trigger signal is output from the drive control unit 37 to the image capturing circuit 31 at the timing set by the region specifying unit 36.

  At this time, the image capturing circuit 31 receives the imaging start trigger signal output from the drive control unit 37, and from the line that has received the signal, out of the number of capture lines specified by the region specifying unit 36, the specified capture start Only the electric signal from the pixel position to the designated capture end pixel position is captured.

  A specific example of the processing here will be described with reference to FIG. In FIG. 5, the scan direction indicates the amount of rotation of the rotary stage 12. Since the line sensor camera 25 does not move with respect to the rotation stage 12 rotating, the image of the subject W has a square shape, and wafer edges appear at both ends along the scanning direction. Inside the wafer edge, an edge cut line in which the surface of the wafer that becomes the object W is exposed after the resist is removed appears. The image capturing circuit 31 captures from the imaging start trigger signal T2 to the capture start pixel position SP21 to the capture end pixel position EP21 and from the capture start pixel position SP22 to the capture end pixel position EP22, and capture lines corresponding to the image length LG3. Finish importing with a number. The inspection areas EA1 and EA2 are sufficiently smaller than the imaging area PA3 of the line sensor camera 25 corresponding to the image length LG3.

  Furthermore, since the imaging start trigger signal T3 is output at a timing corresponding to the position obtained by rotating the rotary stage 12 by 90 °, the image capturing circuit 31 uses the same pixel positions SP21 and EP21 as described above, and the inspection area EA3 and the pixel position. The image of the inspection area EA4 is captured at SP22 and EP22. The examination areas EA3 and EA4 correspond to images at positions rotated by 90 ° around the center of the subject W with respect to the examination objects EA1 and EA2. The image sizes of the inspection areas EA3 and EA4 are sufficiently smaller than the imaging area PA3 of the line sensor camera 25 corresponding to the image length LG3.

The correction unit 32 performs shading correction and distortion correction on the data of only the designated defect area in the same manner as described above. If necessary, the image preprocessing unit 33 performs filtering and the like, and then the original image of the entire subject W Data is constructed and stored in the image storage unit 35.
At this time, in the same manner as described above, the image compression unit 34 compresses the original image data by calculation with the adjacent pixels, and stores the compressed image data in the image storage unit 35.

The image storage unit 35 sends the compressed image data or the original image data to the defect extraction unit 41. The defect extraction unit 41 compares the ideal non-defective image stored in the image storage unit 35, measures the width of the edge cut line of the wafer, and extracts only the defect region where a crack or a foreign substance is generated. The defect area data extracted by the defect extraction unit 41 is sent to the defect classification unit 42, and the defect classification unit 42 reads and compares the defect information stored in advance from the defect dictionary 44 based on the image data of the defect area. Then, the defect type is specified. When a defect registered in the defect dictionary 44 is found, the defect name is assigned to the extracted defect area.
Further, the defect determination unit 43 determines whether or not a defect exists in the subject W from the content of the defect information, and determines whether or not the subject W can be flowed downstream of the production line. After the pass / fail determination is performed by the defect determination unit 43, the original image data, defect information, determination results, and the like of the defect area extracted by the defect extraction unit 41 are stored in the image determination result storage unit 51 of the image storage unit 5. If no defect is extracted by the defect extraction unit 41, the defect determination unit 43 may determine that the defect is good.

  According to this embodiment, when a region to be inspected is determined in advance, by setting the inspection region and starting the inspection, it is possible to efficiently inspect with small capacity image data of only the region necessary for the inspection. . By promptly inspecting the edge cut line, it becomes possible to detect a crack of the subject W at an early stage.

  Note that the present embodiment is not limited to the inspection of the edge cut line, but can be applied to a case where a plurality of inspection points set by the operator are inspected, such as when spiral measurement is performed. Even in such a case, the inspection can be performed promptly.

A third embodiment of the present invention will be described in detail with reference to the drawings.
This embodiment has been made to solve the problem that large defects can be inspected only when a compressed image is inspected, but correct judgment cannot be made depending on the type and size of the defect. It is. Further, the inspection efficiency is improved by automatically classifying the types of defects. Since the apparatus configuration is the same as that of the first embodiment as shown in FIGS. 1 and 2, the description will be omitted and the operation will be described below.

  The transport device or the like takes out a specific subject W from the carrier, and accurately places the subject W on the table 14 with the eccentricity removed. When the subject W is accurately placed on the table 14, the drive control unit 37 in FIG. 1 turns on the adsorption electromagnetic valve 15 to attract and fix the subject W on the table. Thereafter, the drive control unit 37 issues a command to the scan stage drive unit 11 to move the scan stage 10, and moves the peripheral portion of the subject W within the measurement region of the notch detection sensor included in the various sensors 28. Further, the drive control unit 37 issues a command to the rotary stage drive unit 13 to rotate the rotary stage 12. When the notch detection sensor detects the notch at the peripheral edge of the subject W, the position is registered with reference to the position. Thereafter, the rotary stage 12 is rotated so that the rotation position of the subject W is always the same.

When the rotational positions of the notch detection sensor and the rotary stage 12 are determined, the drive control unit 37 issues a command to the scan stage drive unit 11 to move the scan stage 12 on which the subject W is placed on one axis. When the subject W moves uniaxially, it is illuminated at an incident angle θ0 by the light converged by the illumination unit 20 and the cylindrical lens 21 in FIG.
Only a specific wavelength of the light beam reflected from the illuminated straight portion of the subject W is imaged on the line sensor camera 25 by the narrow band filter 26 inserted in the optical system. At this time, when there is a change in film thickness on the surface of the subject W, interference between wavelengths passing through the narrow band filter 26 occurs, and the change in film thickness can be detected as a change in light amount.

  The line sensor camera 25 converts the imaging light into an electrical signal and transmits it to the image capturing circuit 31 for each line. The image capturing circuit 31 converts the electrical signal of each line into data in accordance with the movement of the subject W in the same manner as in the specific example shown in FIG. Further, the correction unit 32 performs shading correction and distortion correction on the data acquired by the image capturing circuit 31. Further, if necessary, after filtering or the like by the image preprocessing unit 33, the original image data of the entire subject W is constructed and stored in the image storage unit 35. At this time, the original image data is compressed by the calculation with the adjacent pixels in the image compression unit 34, and the compressed image data is stored in the image storage unit 35.

  Here, the image storage unit 35 stores a plurality of images of ideal non-defective subjects W. The compressed image data stored in the image storage unit 35 is sent to the defect extraction unit 41 of the image processing unit 4, and compared with an image of the ideal non-defective subject W stored in the image storage unit 35. The object outline image, the outline image of the exposure range, the specific pattern image, and the like, which are images unique to W, are removed, and differences from the image with the non-defective object are extracted by image processing. The predetermined area including the difference is handled as an area (defect area) determined by the defect extraction unit 41 as a defect. The coordinate data of the defect area extracted by the defect extraction unit 41 is sent to the area designation unit 36.

Based on the coordinate data sent to the area designating unit 36, the image storage unit 35 cuts out only the defective area portion from the original image data and sends detailed image data created by cutting out the defective area to the defect classification unit 42. For example, as shown in FIG. 6, when the defect area DA31 defined by the coordinate data exists in the original image I0, the image data corresponding to the defect area DA31 is extracted as detailed image data.
The defect classification unit 42 reads defect information stored in advance based on the detailed image data of the defect area from the defect dictionary 44, compares the defect information, identifies the defect type, and is registered in the identified defect. Give it a name.

  If no defect is extracted by the defect extraction unit 41, the defect determination unit 43 regards it as a non-defective product. If the defect extraction unit 41 extracts a defect, the defect classification unit 42 refers to the defect dictionary 44 and classifies the defect. Then, the type of the defect is specified, and the defect determination unit 43 determines whether or not the defect exists in the subject W from the content of the defect information. Further, it is determined whether or not the subject W can flow downstream of the production line. In the same manner as described above, the original image data, defect information, determination results, and the like of the defect area are stored in the image determination result storage unit 51. Thereafter, the stored defect area image data and the determination result can be referred to at any time by an operation from the operation input unit 29.

  According to the present embodiment, it is possible to save time for transferring large-capacity original image data by extracting defects with appropriate compressed data. At the time of defect extraction, it is not necessary to process the original image data having a large capacity over time. Since defect extraction is performed with compressed data having a small capacity, original image data is extracted only from the extracted defect area, and detailed defects are classified or quality determination is performed, so that defect inspection can be performed efficiently. By using the defect classification unit 42 and the defect dictionary 44, it is possible to perform defect inspection while comparing with defects registered in advance, so that it is easy to confirm defects that occur frequently or defects that are likely to occur in the same place. Become.

The present invention can be widely applied without being limited to the above-described embodiments.
For example, the image data used after designating the defective area is not necessarily the original image data, and may be compressed image data that is compressed as necessary. When inspecting only relatively large defects, the processing time can be shortened.
Although the configuration is such that the entire subject W can be imaged by the line sensor camera 25, in order to further increase the resolution, the subject W may be configured to be imaged in multiple steps.

In the first embodiment, the method in which the angle of the illumination unit 20 is changed with respect to the defect area detected in the compressed image data to re-acquire image data of only the defect area has been described, but the present invention is not limited to this. An apparatus having other observations may be used. You may reacquire a defect area image by different observation methods, such as bright field observation, dark field observation, diffracted light observation, and back surface observation. Further, if the apparatus has other optical conditions, the defect area image may be reacquired under different optical conditions such as changing the type of filter, inserting / extracting a polarizing plate, or changing illumination light.
In addition, by changing the parameter settings (imaging start trigger signal timing, number of capture lines, capture start pixel position, capture end pixel position), it is possible to efficiently inspect even specimens of different sizes, such as small wafers. it can.

It is a block diagram which shows schematic structure of the defect inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the specific structure of the test | inspection part of a defect inspection apparatus. It is a figure explaining the specific example of the process which acquires an original image. It is a figure explaining the specific example of the process which acquires only the image of a defect area | region. It is a figure explaining the specific example of the process which extracts an edge cut line from an original image. It is a figure explaining the specific example of the process which cuts out the image of a defect area | region from an original image.

Explanation of symbols

1 Defect Inspection Device 10 Scan Stage (Holding Unit)
12 Rotating stage (holding part)
14 Table (holding part)
25 Line sensor camera (imaging means)
DESCRIPTION OF SYMBOLS 29 Operation input part 31 Image capture circuit 34 Image compression part 35 Image storage part 36 Area designation part 42 Defect classification part 43 Defect determination part 44 Defect dictionary 51 Image determination result storage part

Claims (9)

Imaging means for capturing image data as optical image information of the subject;
An image compression unit that generates the compressed image data by compressing the image data captured by the imaging unit as an original image;
A defect extraction unit for extracting a defect region including a defect of the subject from the compressed image data;
An area designating unit for designating the defect area extracted by the defect extracting unit,
A defect inspection apparatus for performing defect inspection on original image data of an area specified and acquired by the area specifying unit. A holding unit for holding the subject in a movable manner;
An image capturing unit that captures image data output from the imaging unit and creates an image related to the subject;
The imaging means is a line sensor in which a plurality of imaging elements are arranged in a straight line,
The area designating unit sets the image sensor that captures image data from the plurality of image sensors of the imaging unit, and sets the number of times image data is captured by the image sensor in synchronization with the movement of the holding unit. And
The defect inspection apparatus according to claim 1, wherein the image capturing unit captures an image of a region set by the region designating unit from an output of the image sensor.   2. The imaging device according to claim 1, wherein the imaging unit is configured to be able to change an imaging condition for acquiring an entire image for generating the compressed image data and an imaging condition when an area is designated. Item 3. The defect inspection apparatus according to Item 2.   The defect inspection apparatus according to claim 2, wherein the image capturing unit is configured to be able to acquire an entire image of the subject when an area is not designated.   The said holding | maintenance part has a rotation stage which rotates the said subject circular, The said area designation | designated part is comprised so that the image of the outer edge part of the said subject may be acquired. The defect inspection apparatus according to claim 1.   The defect inspection apparatus according to claim 1, further comprising an image storage unit that stores at least one of the original image data and the compressed image data. A defect classification unit for classifying defects included in the defect area acquired from the original image data, and identifying the type of defect;
A defect dictionary that stores defect information in advance;
A defect determination unit that compares the defect information classified by the defect classification unit with defect information included in the defect dictionary and determines whether the subject is a good product or a defective product;
The defect inspection apparatus according to claim 6, further comprising:   The defect inspection apparatus according to claim 7, further comprising an image determination result storage unit that stores the determination result of the defect determination unit and the image of the defect area used for the determination in a referable manner. The image storage unit for storing the original image data is provided, and uncompressed image data of a defective area is cut out and acquired from the original image data stored in the image storage unit. Defect inspection equipment.

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